- Makes one 6 1/2 x 9 inch layer cake
Want to make a layer cake but don't want all the fuss? Try this sheet cake layer cake—it only takes one baking sheet to make a super fabulous two layer cake! You can never go wrong with the classic combo of lemon on lemon on lemon: lemon cake, lemon buttercream, and lemon curd. All lemon, all the time! —Erin Jeanne McDowell
- Lemon Sheet Cake
sticks (227 g) unsalted butter, at room temperature
(397 g) granulated sugar
zest of 2 lemons
large (284 g) eggs
(5 g) vanilla extract
4 1/2 cups
(512 g) all purpose flour
1 1/2 teaspoons
(9 g) baking soda
(12 g) baking powder
fine sea salt
(227 g) whole milk
(170 g) sour cream
- Filling and Frosting
large (255 g) egg whites
pinch cream of tartar
2 2/3 cups
(510 g) granulated sugar
(227 g) water
(678 g) unsalted butter, at room temperature
(2 g) lemon oil
1 1/2 cups
(about 356 g) prepared lemon curd
lemon zest, as needed for finishing
- Make the cake: preheat the oven to 350° F. Grease a 13x18-inch baking sheet (half sheet pan) with nonstick spray and line with parchment paper. Spray the parchment paper lightly with nonstick spray, too.
- In the bowl of an electric mixer fitted with the paddle attachment, cream the butter, sugar, and lemon zest until light and fluffy, 4-5 minutes.
- Add the eggs one at a time, scraping well after each addition. Add the vanilla and mix to combine.
- In a medium bowl, whisk the flour, baking soda, baking powder, and salt to combine. In a liquid measuring cup, whisk the milk and sour cream to combine.
- Add 1/3 of the flour mixture to the batter and mix to incorporate. Add ½ of the milk mixture and mix to combine. Repeat, adding alternate additions of flour and milk until both are fully incorporated.
- Pour the batter evenly into the prepared pan and bake until a toothpick inserted into the center comes out clean, 25-30 minutes. While the cake is warm, run a small offset spatula or paring knife around the outside edge to loosen it anywhere it’s stuck. Cool completely in the pan.
- While the cakes cool, make the buttercream. Place the egg whites and cream of tartar in the bowl of an electric mixer fitted with the whip attachment.
- Combine the sugar and water in a medium pot and bring to a simmer over medium heat. Stir the mixture until it begins to simmer, then stop stirring and attach a candy thermometer to the side of the pot.
- If any sugar has washed up on the sides of the pot, brush it away with a pastry brush dipped in cool water. Cook the sugar mixture until it reads 235°F on the thermometer.
- When the sugar reaches 235°F, begin whipping the egg whites on medium high speed. The idea is to get them to soft peaks by the time the sugar reaches 245°F.
- When the sugar reaches 245°F, carefully pour it into the mixer in a slow, steady stream while the mixer is running. Continue to whip the mixture until it’s very white, thick, and the bowl is no longer warm to the touch.
- Begin adding the butter to the mixer. If the meringue is still hot, the butter will just melt and the whole thing will be gloopy – so make sure it’s cooled off. Add the butter 1-2 tablespoons at a time, letting each addition incorporate before you add the next. Sometimes, the mixture will look broken about halfway through—just keep whipping, it will come around!
- Add the lemon oil and mix to combine. Taste the buttercream and add more oil to taste. Transfer about 1/4 of the buttercream to a disposable pastry bag and cut a ½ inch opening from the tip.
- To assemble the cake, remove the cake from the baking sheet. Use a sharp serrated knife to cut the cake cleanly in half to create two rectangular layers (13 x 9 inch each).
- Place one cake layer on a serving platter. Pipe a ring of frosting around the edge of the cake to create an icing “retaining wall.” Scoop the lemon curd inside the icing ring, and spread into an even layer.
- Place another cake layer on top and press down gently. Chill the cake for 15-30 minutes.
- Apply a crumb coat to the top and sides of the cake using an offset spatula. Chill for 15-30 minutes.
- Frost the top of the cake, then the sides. Remove the excess “wall” of frosting from the upper edge of the cake by swiping across the surface with the spatula.
- Decorate the cake as desired. I like to pipe a border at the top edge using excess frosting, and top each with some lemon zest. If you have any extra lemon curd, you can spread a thin layer on top of the frosting. Refrigerate the cake not serving right away, but bring to room temp again before serving.